This invention relates to rocket engines, and particularly to such engines which use an oxidizer to combust a fuel.
In a typical liquid rocket engine, fuel and oxidizer are introduced into the combustion chamber through injectors. In rocket engines using liquid oxygen (LOX) as the oxidizer, LOX from the LOX tank is piped to the LOX chamber. The LOX chamber includes a plurality of oxidizer injector tubes through which the oxidizer is injected into the combustion chamber.
The flow rate of LOX to the combustion chamber is controlled by a flow regulating valve in the oxidizer line between the LOX tank and the LOX chamber. In order to optimize mixing and combustion of the fuel and oxidizer, oxidizer flow must be modulated in response to changing engine conditions. Unfortunately, due to the lag time between a change in the flow regulating valve position and the change in oxidizer flow through the injector tubes, mixing and combustion could heretofore only be optimized in a step-wise fashion.
What is needed is a throttleable rocket injector assembly which allows fully variable throttling at the oxidizer injector inlets for optimizing, mixing and combustion of the fuel and oxidizer.
It is therefore an object of the present invention to provide a throttleable rocket injector assembly in which oxidizer flow is controlled at the injector inlets.
According to the present invention, a throttleable rocket injector assembly is disclosed in which the inlet to each of the oxidizer injector tubes is an axially extending slot adjacent the upstream end of each injector tube. A sleeve on each injector tube adjacent the inlet slot thereof is axially positionable between a first position in which oxidizer flow into the injector inlet is unobstructed by the sleeve, and a second position in which the sleeve fully obstructs the injector inlet, preventing the flow of oxidizer therethrough. Each of the sleeves is mounted in a flow positioning plate which constrains the sleeves to move axially in unison.
The positioning plate in turn, is axially positionable by a positioning ring which is secured to the positioning plate by a tongue-and-groove arrangement at the outer diameter of the positioning plate. The outer diameter of the positioning ring is threaded to the inside of the LOX chamber by a large pitch or multi-lead thread on the outer diameter of the positioning ring. Actuators mounted to the inside of the LOX chamber and attached to the positioning ring rotate the positioning ring with respect to the LOX chamber.
The positioning ring thus rotates and translates according to the pitch of the positioning ring/LOX chamber threads. However, since the positioning ring is free to rotate with respect to the positioning plate due to the tongue-and-groove attachment therebetween, only the axial translation of the positioning ring is transmitted to the positioning plate and the sleeves mounted therein. This direct control of oxidizer flow into each of the oxidizer inlets allows fully variable throttling of the oxidizer injectors for optimum mixing and combustion of the fuel and oxidizer, eliminating the need for the step-wise optimization of the prior art.
The foregoing and other features and advantages of the present invention will become more apparent from the following description and accompanying drawings.